One example of conventional double wrap brake band assemblies is shown in FIGS. 1 and 2. A double wrap brake band assembly 1 is provided with a rotating drum 11 and a double wrap brake band 2 arranged on an outer circumference of the rotating drum 11. The double wrap brake band 2 is provided with outside bands 4 and a middle band 3, on which a friction lining 5 is bonded such that the friction lining 5 is frictionally engageable with an outer circumferential surface of the rotating drum 11. The double wrap brake band 2 is also provided with a connecting bar portion 8 to which the outside bands 4 and middle band 3 are connected at one end portions thereof, respectively. The double wrap brake band 2 is further provided with an apply bracket. 6 secured to an end portion of the middle band 3, said end portion being opposite to the end portion connected to the connecting bar portion 8, and also with an anchor bracket 7 secured to end portions of said outside bands 4, said end portions being opposite to the end portions connected to the connecting bar portion 8. The double wrap brake band 2 is anchored at the anchor bracket 7 by an anchor pin 10 illustrated by two-dot chain lines in FIG. 1. Upon application of a load to the apply bracket 6 from an apply pin 9 depicted by two-dot chain lines in FIG. 1, the middle band 3 and outside bands 4 are caused to wrap the rotating drum 11 so that the rotating drum 11 is locked.
A wet-type multiplate clutch and its associated brake band, which are employed when effecting gear change in an automatic transmission, are required to have predetermined frictional characteristics. However, a double wrap brake band assembly has high self-engaging property, thereby making it difficult to control apply loads. It is necessary to apply small binding loads especially in a small torque capacity range. The double wrap bake band assembly is, however, accompanied with a response problem because its apply pin requires a long operating stroke. Moreover, the double wrap brake band assembly has a large torque capacity, thereby making it difficult to control its servo pressure and servo action. Occurrence of variations in servo pressure and servo action tends to develop problems in that the double wrap brake band assembly may not allow a rotating drum to slide to an extent as much as desired or on the contrary, may be brought into a state resembling complete binding and may hence cause a shift shock.